Local Modulation of Single-Atomic Mn Sites for Enhanced Ambient Ammonia Electrosynthesis
Local Modulation of Single-Atomic Mn Sites for Enhanced Ambient Ammonia Electrosynthesis
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DOI：
10.1021/acscatal.0c04102
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发表时间：
2021-01-15
期刊：
影响因子：
12.9
通讯作者：
Xin, Huolin L.
中科院分区：
文献类型：
--
作者：
Han, Lili;Hou, Machuan;Xin, Huolin L.
合理调控电催化N-2还原反应单原子活性中心的局域结构是一个迫切而又值得研究的课题。在此，我们通过精细控制Mn-O键合条件，实现了单原子Mn位的局域调制，并在多孔碳（Mn-O3 N1/PC）上构建了单原子Mn-O3 N1位。所构建的结构通过原子尺度成像、拉曼光谱、基于同步辐射的软X射线吸收光谱和硬X射线吸收光谱以及X射线光电子能谱的组合来确认。Mn-O3 N1/PC催化剂在-0.35 V下相对于可逆氢电极产生66.41 μ g h（-1）mg（cat）（-1）（对应于1.56 mg h（-1）mg（cat）（-1））的NH3产率，这是在对照Mn-N-4/PC催化剂上的约4倍。NRR性能的增强归因于其独特的几何结构和电子结构，这不仅有利于N-2分子的吸附和活化，而且降低了电位决定步骤的自由能变化。
Rationally tuning the local structures of single-atomtc active sites for the electrocatalytic N-2 reduction reaction (NRR) remains an urgent but worthwhile research topic. Herein, we accomplish the local modulation of single-atomic Mn sites and construct single Mn-O3N1 sites anchored on porous carbon Mn-O3N1/PC) by delicately controlling the Mn-O bonding conditions. The constructed structures are confirmed via the combination of atomic-scale imaging, Raman spectroscopy, synchrotron radiation-based soft and hard X-ray absorption spectroscopies, and X-ray photoelectron spectroscopy. The Mn-O3N1/PC catalyst yields an NH3 yield rate of 66.41 mu g h(-1) mg(cat)(-1) (corresponding to 1.56 mg h(-1) mg(cat)(-1)) at -0.35 V versus reversible hydrogen electrode, which is about four times that on the control Mn-N-4/PC catalyst. The enhanced NRR performance is ascribed to its unique geometry and electronic structures, which not only facilitate the adsorption and activation of the N-2 molecule but also lower the free energy change of the potential-determining step.